agora inbox for pgsql-hackers@postgresql.org  
help / color / mirror / Atom feed
[PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
370+ messages / 2 participants
[nested] [flat]

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

Add WITH OLD DATA to keep the current data when replacing a materialized
view which is useful when running REFRESH MATERIALIZED VIEW CONCURRENTLY
afterwards.
---
 .../sgml/ref/create_materialized_view.sgml    |  30 +-
 src/backend/commands/createas.c               | 229 +++++++++++++++-
 src/backend/commands/matview.c                |  80 ++++++
 src/backend/commands/tablecmds.c              |  11 +-
 src/backend/parser/gram.y                     |  25 ++
 src/bin/psql/tab-complete.in.c                |  38 ++-
 src/include/commands/matview.h                |   2 +
 src/include/nodes/parsenodes.h                |   4 +-
 src/include/nodes/primnodes.h                 |  10 +
 src/test/regress/expected/matview.out         | 258 ++++++++++++++++++
 src/test/regress/sql/matview.sql              | 152 +++++++++++
 src/tools/pgindent/typedefs.list              |   1 +
 12 files changed, 813 insertions(+), 27 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..e6c7b7c7d37 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,13 +21,13 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
     [ TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> ]
     AS <replaceable>query</replaceable>
-    [ WITH [ NO ] DATA ]
+    [ WITH [ NO | OLD ] DATA ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -37,7 +37,8 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <para>
    <command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
    a query.  The query is executed and used to populate the view at the time
-   the command is issued (unless <command>WITH NO DATA</command> is used) and may be
+   the command is issued (unless <command>WITH NO DATA</command> or
+   <command>WITH OLD DATA</command> is used) and may be
    refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
   </para>
 
@@ -60,6 +61,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +79,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unlike when using <literal>OR REPLACE</literal>.
      </para>
     </listitem>
    </varlistentry>
@@ -151,7 +163,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>WITH [ NO ] DATA</literal></term>
+    <term><literal>WITH [ NO | OLD ] DATA</literal></term>
     <listitem>
      <para>
       This clause specifies whether or not the materialized view should be
@@ -159,6 +171,14 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       flagged as unscannable and cannot be queried until <command>REFRESH
       MATERIALIZED VIEW</command> is used.
      </para>
+
+     <para>
+      The form <command>WITH OLD DATA</command> keeps the already stored data
+      when replacing an existing materialized view to keep it populated.  Use
+      this form if you want to use <command>REFRESH MATERIALIZED VIEW CONCURRENTLY</command>
+      as it requires a populated materialized view.  It is an error to use this
+      form when creating a new materialized view.
+     </para>
     </listitem>
    </varlistentry>
 
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6dbb831ca89..cbc384dd3f7 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -34,9 +34,11 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/queryjumble.h"
@@ -63,6 +65,7 @@ typedef struct
 /* utility functions for CTAS definition creation */
 static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
 static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+static ObjectAddress create_ctas_replace(List *tlist, IntoClause *into, Oid matviewOid);
 
 /* DestReceiver routines for collecting data */
 static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
@@ -70,6 +73,7 @@ static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
 static void intorel_shutdown(DestReceiver *self);
 static void intorel_destroy(DestReceiver *self);
 
+static bool CreateTableAsRelReplaceable(CreateTableAsStmt *ctas);
 
 /*
  * create_ctas_internal
@@ -157,6 +161,8 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 	List	   *attrList;
 	ListCell   *t,
 			   *lc;
+	bool		is_matview = (into->viewQuery != NULL);
+	Oid			matviewOid = InvalidOid;
 
 	/*
 	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
@@ -211,8 +217,146 @@ create_ctas_nodata(List *tlist, IntoClause *into)
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("too many column names were specified")));
 
-	/* Create the relation definition using the ColumnDef list */
-	return create_ctas_internal(attrList, into);
+	/* Get the existing matview to be replaced */
+	if (is_matview && into->replace)
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel,
+													AccessExclusiveLock,
+													&matviewOid);
+
+	if (OidIsValid(matviewOid))
+		/* Replace the existing matview */
+		return create_ctas_replace(attrList, into, matviewOid);
+	else
+		/* Create the relation definition using the ColumnDef list */
+		return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * create_ctas_replace
+ *
+ * Internal utility used for replacing the definition of a materialized view.
+ * Caller needs to provide a list of attributes (ColumnDef nodes) and the
+ * materialized view OID.
+ */
+static ObjectAddress
+create_ctas_replace(List *attrList, IntoClause *into, Oid matviewOid)
+{
+	ObjectAddress intoRelationAddr;
+	Relation	rel;
+	List	   *atcmds = NIL;
+	AlterTableCmd *atcmd;
+	TupleDesc	descriptor;
+	Query	   *query;
+
+	/* Relation is already locked, but we must build a relcache entry. */
+	rel = relation_open(matviewOid, NoLock);
+
+	/* Make sure it *is* a matview. */
+	if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a materialized view",
+					   RelationGetRelationName(rel)));
+
+	/* Also check it's not in use already */
+	CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+	descriptor = BuildDescForRelation(attrList);
+	checkMatviewColumns(descriptor, rel->rd_att);
+
+	/*
+	 * If new attributes have been added, we must add pg_attribute entries for
+	 * them.  It is convenient (although overkill) to use the ALTER TABLE ADD
+	 * COLUMN infrastructure for this.
+	 *
+	 * Note that we must do this before updating the query for the matview,
+	 * since the rules system requires that the correct matview columns be in
+	 * place when defining the new rules.
+	 *
+	 * Also note that ALTER TABLE doesn't run parse transformation on
+	 * AT_AddColumnToView commands.  The ColumnDef we supply must be ready to
+	 * execute as-is.
+	 */
+	if (list_length(attrList) > rel->rd_att->natts)
+	{
+		ListCell   *c;
+
+		for_each_from(c, attrList, rel->rd_att->natts)
+		{
+			atcmd = makeNode(AlterTableCmd);
+			atcmd->subtype = AT_AddColumnToView;
+			atcmd->def = (Node *) lfirst(c);
+			atcmds = lappend(atcmds, atcmd);
+		}
+	}
+
+	/*
+	 * Use ALTER TABLE to set access method, tablespace, and storage options.
+	 * When replacing an existing matview we need to alter the relation such
+	 * that the defaults apply as if they have not been specified at all by
+	 * the CREATE OR REPLACE MATERIALIZED VIEW statement.
+	 */
+
+	/* access method */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetAccessMethod;
+	atcmd->name = into->accessMethod
+		? into->accessMethod : default_table_access_method;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* tablespace */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_SetTableSpace;
+	if (into->tableSpaceName)
+		atcmd->name = into->tableSpaceName;
+	else
+	{
+		Oid			spcOid;
+		char	   *spcName;
+
+		/*
+		 * Must use the default tablespace if no explicit tablespace is
+		 * specified.
+		 */
+		spcOid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+		if (!OidIsValid(spcOid))
+			spcOid = MyDatabaseTableSpace;
+
+		spcName = get_tablespace_name(spcOid);
+		if (!spcName)			/* should not happen */
+			elog(ERROR, "could not find tuple for tablespace %u", spcOid);
+
+		atcmd->name = spcName;
+	}
+	atcmds = lappend(atcmds, atcmd);
+
+	/* storage options */
+	atcmd = makeNode(AlterTableCmd);
+	atcmd->subtype = AT_ReplaceRelOptions;
+	atcmd->def = (Node *) into->options;
+	atcmds = lappend(atcmds, atcmd);
+
+	/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
+	AlterTableInternal(matviewOid, atcmds, true);
+
+	/* Make the new matview columns visible */
+	CommandCounterIncrement();
+
+	relation_close(rel, NoLock);
+	ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+
+	/*
+	 * Replace the "view" part of the matview.  StoreViewQuery scribbles on
+	 * tree, so make a copy.
+	 */
+	query = copyObject(into->viewQuery);
+	StoreViewQuery(intoRelationAddr.objectId, query, true);
+
+	/* Make the new matview query visible */
+	CommandCounterIncrement();
+
+	return intoRelationAddr;
 }
 
 
@@ -232,8 +376,37 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	DestReceiver *dest;
 	ObjectAddress address;
 
-	/* Check if the relation exists or not */
-	if (CreateTableAsRelExists(stmt))
+	/*
+	 * Check if the relation exists or not.  An existing materialized view can
+	 * be replaced.
+	 */
+	if (is_matview && into->replace)
+	{
+		if (CreateTableAsRelReplaceable(stmt))
+		{
+			/* Change the relation to match the new query and other options. */
+			address = create_ctas_nodata(query->targetList, into);
+
+			/*
+			 * Refresh the materialized view with a fake statement unless we
+			 * must keep the old data.
+			 */
+			if (into->data != WITHDATA_OLD)
+			{
+				RefreshMatViewStmt *refresh;
+
+				refresh = makeNode(RefreshMatViewStmt);
+				refresh->relation = into->rel;
+				refresh->skipData = into->skipData;
+				refresh->concurrent = false;
+
+				address = ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+			}
+
+			return address;
+		}
+	}
+	else if (CreateTableAsRelExists(stmt))
 		return InvalidObjectAddress;
 
 	/*
@@ -273,6 +446,11 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 	 */
 	if (is_matview)
 	{
+		if (into->data == WITHDATA_OLD)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("must not specify WITH OLD DATA when creating a new materialized view")));
+
 		do_refresh = !into->skipData;
 		into->skipData = true;
 	}
@@ -429,6 +607,49 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	return false;
 }
 
+/*
+ * CreateTableAsRelReplaceable --- check existence of replaceable relation for
+ * CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the relation
+ * exists and should be replaced, otherwise false.
+ */
+static bool
+CreateTableAsRelReplaceable(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!into->replace)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and OR REPLACE has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
 /*
  * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
  *
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index f7d8007f796..853eae37057 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -967,3 +967,83 @@ CloseMatViewIncrementalMaintenance(void)
 	matview_maintenance_depth--;
 	Assert(matview_maintenance_depth >= 0);
 }
+
+/*
+ * Verify that the columns associated with proposed new matview definition
+ * match the columns of the old matview.  This is similar to equalRowTypes(),
+ * with code added to generate specific complaints.  Also, we allow the new
+ * matview to have more columns than the old.
+ */
+void
+checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc)
+{
+	int			i;
+
+	if (newdesc->natts < olddesc->natts)
+	{
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				errmsg("cannot drop columns from materialized view"));
+	}
+
+	for (i = 0; i < olddesc->natts; i++)
+	{
+		Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
+		Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
+
+		/* XXX msg not right, but we don't support DROP COL on matview anyway */
+		if (newattr->attisdropped != oldattr->attisdropped)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		}
+
+		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   NameStr(newattr->attname)),
+					errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+		}
+
+		/*
+		 * We cannot allow type, typmod, or collation to change, since these
+		 * properties may be embedded in Vars of other views/rules referencing
+		 * this one.  Other column attributes can be ignored.
+		 */
+		if (newattr->atttypid != oldattr->atttypid ||
+			newattr->atttypmod != oldattr->atttypmod)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+						   NameStr(oldattr->attname),
+						   format_type_with_typemod(oldattr->atttypid,
+													oldattr->atttypmod),
+						   format_type_with_typemod(newattr->atttypid,
+													newattr->atttypmod)));
+		}
+
+		/*
+		 * At this point, attcollations should be both valid or both invalid,
+		 * so applying get_collation_name unconditionally should be fine.
+		 */
+		if (newattr->attcollation != oldattr->attcollation)
+		{
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+						   NameStr(oldattr->attname),
+						   get_collation_name(oldattr->attcollation),
+						   get_collation_name(newattr->attcollation)));
+		}
+	}
+
+	/*
+	 * We ignore the constraint fields since the new matview desc can't have
+	 * any constraints.
+	 */
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 472db112fa7..5bf322257c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4720,7 +4720,8 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE
+										 * [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -5020,8 +5021,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5458,7 +5460,8 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED]
+									 * VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e1388c55..91e52689d7a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -250,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	Alias	   *alias;
 	RangeVar   *range;
 	IntoClause *into;
+	WithDataOption withdata;
 	WithClause *with;
 	InferClause	*infer;
 	OnConflictClause *onconflict;
@@ -358,6 +359,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_grant_grant_option
 				opt_nowait opt_if_exists opt_with_data
 				opt_transaction_chain
+%type <withdata> opt_with_no_or_old_data
 %type <list>	grant_role_opt_list
 %type <defelt>	grant_role_opt
 %type <node>	grant_role_opt_value
@@ -5030,6 +5032,13 @@ opt_with_data:
 			| /*EMPTY*/								{ $$ = true; }
 		;
 
+opt_with_no_or_old_data:
+			WITH DATA_P								{ $$ = WITHDATA_DEFAULT; }
+			| WITH NO DATA_P						{ $$ = WITHDATA_NONE; }
+			| WITH OLD DATA_P						{ $$ = WITHDATA_OLD; }
+			| /*EMPTY*/								{ $$ = WITHDATA_DEFAULT; }
+		;
+
 
 /*****************************************************************************
  *
@@ -5067,6 +5076,22 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_no_or_old_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = $10 == WITHDATA_NONE;
+					$7->data = $10;
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 46b9add0604..e683e4b1b33 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2225,7 +2225,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4256,28 +4256,42 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or
+	 * USING
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
-	 * methods
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list
+	 * of access methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+
+	/*
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access
+	 * method> with AS
+	 */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
-	 * with "SELECT"
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access
+	 * method> ] AS with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/matview.h b/src/include/commands/matview.h
index 738c731c1a9..140f7e96696 100644
--- a/src/include/commands/matview.h
+++ b/src/include/commands/matview.h
@@ -33,4 +33,6 @@ extern DestReceiver *CreateTransientRelDestReceiver(Oid transientoid);
 
 extern bool MatViewIncrementalMaintenanceIsEnabled(void);
 
+extern void checkMatviewColumns(TupleDesc newdesc, TupleDesc olddesc);
+
 #endif							/* MATVIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 4133c404a6b..7c629d09fb1 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2519,7 +2519,8 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE
+								 * [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
@@ -4595,5 +4596,4 @@ typedef struct WaitStmt
 	List	   *options;		/* List of DefElem nodes */
 } WaitStmt;
 
-
 #endif							/* PARSENODES_H */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index bb05aeebee4..3b916993dbe 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -147,6 +147,14 @@ typedef struct TableFunc
 	ParseLoc	location;
 } TableFunc;
 
+/* WITH DATA option of CREATE MATERIALIZED VIEW */
+typedef enum WithDataOption
+{
+	WITHDATA_DEFAULT,			/* WITH DATA */
+	WITHDATA_NONE,				/* WITH NO DATA */
+	WITHDATA_OLD,				/* WITH OLD DATA */
+} WithDataOption;
+
 /*
  * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
  * CREATE MATERIALIZED VIEW
@@ -170,6 +178,8 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	WithDataOption data;		/* WITH [ NO | OLD ] DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 0355720dfc6..e923aa4f0a7 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -699,3 +699,261 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 5
+(1 row)
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+ERROR:  must not specify WITH OLD DATA when creating a new materialized view
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+ c9 
+----
+ 
+(1 row)
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+ERROR:  domain mvtest_dom does not allow null values
+SELECT a FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 934426b9ae8..abc354a13f8 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -318,3 +318,155 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- Test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- Matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- Replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Replace query but keep old data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 5 AS a
+  WITH OLD DATA;
+SELECT * FROM mvtest_replace;
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- Add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- Replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- Restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- Can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- Index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- Cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- Cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- Cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- Must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- Cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
+
+-- Clause WITH OLD DATA is not allowed when creating a new matview
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 17 AS a
+  WITH OLD DATA; -- error
+
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8;
+-- Add a ninth column (exceeding the old t_bits)
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS c1, 2 AS c2, 3 AS c3, 4 AS c4,
+         5 AS c5, 6 AS c6, 7 AS c7, null AS c8,
+         null AS c9
+  WITH OLD DATA;
+SELECT c9 FROM mvtest_replace;
+
+-- Test constraint violation on WITH OLD DATA
+DROP MATERIALIZED VIEW mvtest_replace;
+CREATE DOMAIN mvtest_dom AS int
+  CONSTRAINT mvtest_dom_nn NOT NULL;
+CREATE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1::mvtest_dom AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2::mvtest_dom AS a, 3::mvtest_dom AS b
+  WITH OLD DATA; -- error: new column "b" cannot be null
+SELECT a FROM mvtest_replace;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c5db6ca6705..2223a658899 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -3471,6 +3471,7 @@ WindowStatePerFunc
 WindowStatePerFuncData
 WithCheckOption
 WithClause
+WithDataOption
 WordBoundaryNext
 WordEntry
 WordEntryIN
-- 
2.54.0


--5k2efyjyy5ysz4p6--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW
@ 2024-05-21 16:35  Erik Wienhold <ewie@ewie.name>
  0 siblings, 0 replies; 370+ messages in thread

From: Erik Wienhold @ 2024-05-21 16:35 UTC (permalink / raw)

---
 .../sgml/ref/create_materialized_view.sgml    |  15 +-
 src/backend/commands/createas.c               | 219 ++++++++++++++----
 src/backend/commands/tablecmds.c              |   8 +-
 src/backend/commands/view.c                   | 106 ++++++---
 src/backend/parser/gram.y                     |  15 ++
 src/bin/psql/tab-complete.in.c                |  26 ++-
 src/include/commands/view.h                   |   3 +
 src/include/nodes/parsenodes.h                |   2 +-
 src/include/nodes/primnodes.h                 |   1 +
 src/test/regress/expected/matview.out         | 205 ++++++++++++++++
 src/test/regress/sql/matview.sql              | 117 ++++++++++
 11 files changed, 624 insertions(+), 93 deletions(-)

diff --git a/doc/src/sgml/ref/create_materialized_view.sgml b/doc/src/sgml/ref/create_materialized_view.sgml
index 62d897931c3..5e03320eb73 100644
--- a/doc/src/sgml/ref/create_materialized_view.sgml
+++ b/doc/src/sgml/ref/create_materialized_view.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
+CREATE [ OR REPLACE ] MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ USING <replaceable class="parameter">method</replaceable> ]
     [ WITH ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] ) ]
@@ -60,6 +60,17 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>OR REPLACE</literal></term>
+    <listitem>
+     <para>
+      Replaces a materialized view if it already exists.
+      Specifying <literal>OR REPLACE</literal> together with
+      <literal>IF NOT EXISTS</literal> is an error.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>IF NOT EXISTS</literal></term>
     <listitem>
@@ -67,7 +78,7 @@ CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] <replaceable>table_name</replaceable>
       Do not throw an error if a materialized view with the same name already
       exists. A notice is issued in this case.  Note that there is no guarantee
       that the existing materialized view is anything like the one that would
-      have been created.
+      have been created, unless you use <literal>OR REPLACE</literal> instead.
      </para>
     </listitem>
    </varlistentry>
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1620273f965 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -24,6 +24,7 @@
  */
 #include "postgres.h"
 
+#include "miscadmin.h"
 #include "access/heapam.h"
 #include "access/reloptions.h"
 #include "access/tableam.h"
@@ -34,6 +35,7 @@
 #include "commands/matview.h"
 #include "commands/prepare.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/view.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -81,55 +83,161 @@ static void intorel_destroy(DestReceiver *self);
 static ObjectAddress
 create_ctas_internal(List *attrList, IntoClause *into)
 {
-	CreateStmt *create = makeNode(CreateStmt);
-	bool		is_matview;
+	bool		is_matview,
+				replace = false;
 	char		relkind;
-	Datum		toast_options;
-	const char *const validnsps[] = HEAP_RELOPT_NAMESPACES;
+	Oid			matviewOid = InvalidOid;
 	ObjectAddress intoRelationAddr;
 
 	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
 	is_matview = (into->viewQuery != NULL);
 	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
 
-	/*
-	 * Create the target relation by faking up a CREATE TABLE parsetree and
-	 * passing it to DefineRelation.
-	 */
-	create->relation = into->rel;
-	create->tableElts = attrList;
-	create->inhRelations = NIL;
-	create->ofTypename = NULL;
-	create->constraints = NIL;
-	create->options = into->options;
-	create->oncommit = into->onCommit;
-	create->tablespacename = into->tableSpaceName;
-	create->if_not_exists = false;
-	create->accessMethod = into->accessMethod;
+	/* Check if an existing materialized view needs to be replaced. */
+	if (is_matview)
+	{
+		LOCKMODE	lockmode;
 
-	/*
-	 * Create the relation.  (This will error out if there's an existing view,
-	 * so we don't need more code to complain if "replace" is false.)
-	 */
-	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+		lockmode = into->replace ? AccessExclusiveLock : NoLock;
+		(void) RangeVarGetAndCheckCreationNamespace(into->rel, lockmode,
+													&matviewOid);
+		replace = OidIsValid(matviewOid) && into->replace;
+	}
 
-	/*
-	 * If necessary, create a TOAST table for the target table.  Note that
-	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
-	 * that the TOAST table will be visible for insertion.
-	 */
-	CommandCounterIncrement();
+	if (is_matview && replace)
+	{
+		Relation	rel;
+		List	   *atcmds = NIL;
+		AlterTableCmd *atcmd;
+		TupleDesc	descriptor;
+
+		rel = relation_open(matviewOid, NoLock);
+
+		if (rel->rd_rel->relkind != RELKIND_MATVIEW)
+			ereport(ERROR,
+					errcode(ERRCODE_WRONG_OBJECT_TYPE),
+					errmsg("\"%s\" is not a materialized view",
+						   RelationGetRelationName(rel)));
+
+		CheckTableNotInUse(rel, "CREATE OR REPLACE MATERIALIZED VIEW");
+
+		descriptor = BuildDescForRelation(attrList);
+		checkViewColumns(descriptor, rel->rd_att, true);
+
+		/* add new attributes */
+		if (list_length(attrList) > rel->rd_att->natts)
+		{
+			ListCell   *c;
+			int			skip = rel->rd_att->natts;
+
+			foreach(c, attrList)
+			{
+				if (skip > 0)
+				{
+					skip--;
+					continue;
+				}
+				atcmd = makeNode(AlterTableCmd);
+				atcmd->subtype = AT_AddColumnToView;
+				atcmd->def = (Node *) lfirst(c);
+				atcmds = lappend(atcmds, atcmd);
+			}
+		}
+
+		/*
+		 * The following alters access method, tablespace, and storage options.
+		 * When replacing an existing matview we need to alter the relation
+		 * such that the defaults apply as if they have not been specified at
+		 * all by the CREATE statement.
+		 */
+
+		/* access method */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetAccessMethod;
+		atcmd->name = into->accessMethod ? into->accessMethod : default_table_access_method;
+		atcmds = lappend(atcmds, atcmd);
+
+		/* tablespace */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_SetTableSpace;
+		if (into->tableSpaceName != NULL)
+			atcmd->name = into->tableSpaceName;
+		else
+		{
+			Oid spcid;
+
+			/*
+			 * Resolve the name of the default or database tablespace because
+			 * we need to specify the tablespace by name.
+			 *
+			 * TODO: Move that to ATPrepSetTableSpace? Must allow AlterTableCmd.name to be NULL then.
+			 */
+			spcid = GetDefaultTablespace(RELPERSISTENCE_PERMANENT, false);
+			if (!OidIsValid(spcid))
+				spcid = MyDatabaseTableSpace;
+			atcmd->name = get_tablespace_name(spcid);
+		}
+		atcmds = lappend(atcmds, atcmd);
+
+		/* storage options */
+		atcmd = makeNode(AlterTableCmd);
+		atcmd->subtype = AT_ReplaceRelOptions;
+		atcmd->def = (Node *) into->options;
+		atcmds = lappend(atcmds, atcmd);
+
+		AlterTableInternal(matviewOid, atcmds, true);
+		CommandCounterIncrement();
+
+		relation_close(rel, NoLock);
+		ObjectAddressSet(intoRelationAddr, RelationRelationId, matviewOid);
+	}
+	else
+	{
+		CreateStmt *create = makeNode(CreateStmt);
+		Datum		toast_options;
+		const static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+
+		/*
+		 * Create the target relation by faking up a CREATE TABLE parsetree
+		 * and passing it to DefineRelation.
+		 */
+		create->relation = into->rel;
+		create->tableElts = attrList;
+		create->inhRelations = NIL;
+		create->ofTypename = NULL;
+		create->constraints = NIL;
+		create->options = into->options;
+		create->oncommit = into->onCommit;
+		create->tablespacename = into->tableSpaceName;
+		create->if_not_exists = false;
+		create->accessMethod = into->accessMethod;
+
+		/*
+		 * Create the relation.  (This will error out if there's an existing
+		 * view, so we don't need more code to complain if "replace" is
+		 * false.)
+		 */
+		intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL,
+										  NULL);
 
-	/* parse and validate reloptions for the toast table */
-	toast_options = transformRelOptions((Datum) 0,
-										create->options,
-										"toast",
-										validnsps,
-										true, false);
+		/*
+		 * If necessary, create a TOAST table for the target table.  Note that
+		 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+		 * that the TOAST table will be visible for insertion.
+		 */
+		CommandCounterIncrement();
+
+		/* parse and validate reloptions for the toast table */
+		toast_options = transformRelOptions((Datum) 0,
+											create->options,
+											"toast",
+											validnsps,
+											true, false);
 
-	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+		(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
 
-	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+		NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+	}
 
 	/* Create the "view" part of a materialized view. */
 	if (is_matview)
@@ -137,7 +245,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 		/* StoreViewQuery scribbles on tree, so make a copy */
 		Query	   *query = copyObject(into->viewQuery);
 
-		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		StoreViewQuery(intoRelationAddr.objectId, query, replace);
 		CommandCounterIncrement();
 	}
 
@@ -234,7 +342,26 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 	/* Check if the relation exists or not */
 	if (CreateTableAsRelExists(stmt))
+	{
+		/* An existing materialized view can be replaced. */
+		if (is_matview && into->replace)
+		{
+			RefreshMatViewStmt *refresh;
+
+			/* Change the relation to match the new query and other options. */
+			(void) create_ctas_nodata(query->targetList, into);
+
+			/* Refresh the materialized view with a fake statement. */
+			refresh = makeNode(RefreshMatViewStmt);
+			refresh->relation = into->rel;
+			refresh->skipData = into->skipData;
+			refresh->concurrent = false;
+
+			return ExecRefreshMatView(refresh, pstate->p_sourcetext, qc);
+		}
+
 		return InvalidObjectAddress;
+	}
 
 	/*
 	 * Create the tuple receiver object and insert info it will need
@@ -402,14 +529,15 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 	oldrelid = get_relname_relid(into->rel->relname, nspid);
 	if (OidIsValid(oldrelid))
 	{
-		if (!ctas->if_not_exists)
+		if (!ctas->if_not_exists && !into->replace)
 			ereport(ERROR,
 					(errcode(ERRCODE_DUPLICATE_TABLE),
 					 errmsg("relation \"%s\" already exists",
 							into->rel->relname)));
 
 		/*
-		 * The relation exists and IF NOT EXISTS has been specified.
+		 * The relation exists and IF NOT EXISTS or OR REPLACE has been
+		 * specified.
 		 *
 		 * If we are in an extension script, insist that the pre-existing
 		 * object be a member of the extension, to avoid security risks.
@@ -417,11 +545,12 @@ CreateTableAsRelExists(CreateTableAsStmt *ctas)
 		ObjectAddressSet(address, RelationRelationId, oldrelid);
 		checkMembershipInCurrentExtension(&address);
 
-		/* OK to skip */
-		ereport(NOTICE,
-				(errcode(ERRCODE_DUPLICATE_TABLE),
-				 errmsg("relation \"%s\" already exists, skipping",
-						into->rel->relname)));
+		if (ctas->if_not_exists)
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists, skipping",
+							into->rel->relname)));
 		return true;
 	}
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cb811520c29..44dcd2c5b0d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4645,7 +4645,7 @@ AlterTableGetLockLevel(List *cmds)
 				 * Subcommands that may be visible to concurrent SELECTs
 				 */
 			case AT_DropColumn: /* change visible to SELECT */
-			case AT_AddColumnToView:	/* CREATE VIEW */
+			case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			case AT_DropOids:	/* used to equiv to DropColumn */
 			case AT_EnableAlwaysRule:	/* may change SELECT rules */
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
@@ -4940,8 +4940,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
-			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW);
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
+			ATSimplePermissions(cmd->subtype, rel, ATT_VIEW | ATT_MATVIEW);
 			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
 							lockmode, context);
 			/* Recursion occurs during execution phase */
@@ -5372,7 +5372,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 	switch (cmd->subtype)
 	{
 		case AT_AddColumn:		/* ADD COLUMN */
-		case AT_AddColumnToView:	/* add column via CREATE OR REPLACE VIEW */
+		case AT_AddColumnToView:	/* via CREATE OR REPLACE [MATERIALIZED] VIEW */
 			address = ATExecAddColumn(wqueue, tab, rel, &cmd,
 									  cmd->recurse, false,
 									  lockmode, cur_pass, context);
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6f0301555e0..53d4cacc4c1 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -30,8 +30,6 @@
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 
-static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
-
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
@@ -129,7 +127,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		 * column list.
 		 */
 		descriptor = BuildDescForRelation(attrList);
-		checkViewColumns(descriptor, rel->rd_att);
+		checkViewColumns(descriptor, rel->rd_att, false);
 
 		/*
 		 * If new attributes have been added, we must add pg_attribute entries
@@ -263,15 +261,22 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
  * added to generate specific complaints.  Also, we allow the new view to have
  * more columns than the old.
  */
-static void
-checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
+void
+checkViewColumns(TupleDesc newdesc, TupleDesc olddesc, bool is_matview)
 {
 	int			i;
 
 	if (newdesc->natts < olddesc->natts)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("cannot drop columns from view")));
+	{
+		if (is_matview)
+			ereport(ERROR,
+					errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					errmsg("cannot drop columns from materialized view"));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot drop columns from view")));
+	}
 
 	for (i = 0; i < olddesc->natts; i++)
 	{
@@ -280,17 +285,34 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 
 		/* XXX msg not right, but we don't support DROP COL on view anyway */
 		if (newattr->attisdropped != oldattr->attisdropped)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot drop columns from view")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot drop columns from materialized view"));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot drop columns from view")));
+		}
 
 		if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change name of view column \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							NameStr(newattr->attname)),
-					 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change name of materialized view column \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   NameStr(newattr->attname)),
+						errhint("Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead."));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change name of view column \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								NameStr(newattr->attname)),
+						 errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
+		}
 
 		/*
 		 * We cannot allow type, typmod, or collation to change, since these
@@ -299,26 +321,48 @@ checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
 		 */
 		if (newattr->atttypid != oldattr->atttypid ||
 			newattr->atttypmod != oldattr->atttypmod)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change data type of view column \"%s\" from %s to %s",
-							NameStr(oldattr->attname),
-							format_type_with_typemod(oldattr->atttypid,
-													 oldattr->atttypmod),
-							format_type_with_typemod(newattr->atttypid,
-													 newattr->atttypmod))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change data type of materialized view column \"%s\" from %s to %s",
+							   NameStr(oldattr->attname),
+							   format_type_with_typemod(oldattr->atttypid,
+														oldattr->atttypmod),
+							   format_type_with_typemod(newattr->atttypid,
+														newattr->atttypmod)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change data type of view column \"%s\" from %s to %s",
+								NameStr(oldattr->attname),
+								format_type_with_typemod(oldattr->atttypid,
+														 oldattr->atttypmod),
+								format_type_with_typemod(newattr->atttypid,
+														 newattr->atttypmod))));
+		}
 
 		/*
 		 * At this point, attcollations should be both valid or both invalid,
 		 * so applying get_collation_name unconditionally should be fine.
 		 */
 		if (newattr->attcollation != oldattr->attcollation)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
-							NameStr(oldattr->attname),
-							get_collation_name(oldattr->attcollation),
-							get_collation_name(newattr->attcollation))));
+		{
+			if (is_matview)
+				ereport(ERROR,
+						errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						errmsg("cannot change collation of materialized view column \"%s\" from \"%s\" to \"%s\"",
+							   NameStr(oldattr->attname),
+							   get_collation_name(oldattr->attcollation),
+							   get_collation_name(newattr->attcollation)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
+								NameStr(oldattr->attname),
+								get_collation_name(oldattr->attcollation),
+								get_collation_name(newattr->attcollation))));
+		}
 	}
 
 	/*
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index db43034b9db..7aaf0e37ad8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4929,6 +4929,21 @@ CreateMatViewStmt:
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
 				}
+		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
+				{
+					CreateTableAsStmt *ctas = makeNode(CreateTableAsStmt);
+
+					ctas->query = $9;
+					ctas->into = $7;
+					ctas->objtype = OBJECT_MATVIEW;
+					ctas->is_select_into = false;
+					ctas->if_not_exists = false;
+					/* cram additional flags into the IntoClause */
+					$7->rel->relpersistence = $4;
+					$7->skipData = !($10);
+					$7->replace = true;
+					$$ = (Node *) ctas;
+				}
 		;
 
 create_mv_target:
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 1f2ca946fc5..f49f0b60c95 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -2187,7 +2187,7 @@ match_previous_words(int pattern_id,
 	/* complete with something you can create or replace */
 	else if (TailMatches("CREATE", "OR", "REPLACE"))
 		COMPLETE_WITH("FUNCTION", "PROCEDURE", "LANGUAGE", "RULE", "VIEW",
-					  "AGGREGATE", "TRANSFORM", "TRIGGER");
+					  "AGGREGATE", "TRANSFORM", "TRIGGER", "MATERIALIZED VIEW");
 
 /* DROP, but not DROP embedded in other commands */
 	/* complete with something you can drop */
@@ -4072,28 +4072,34 @@ match_previous_words(int pattern_id,
 		COMPLETE_WITH("SELECT");
 
 /* CREATE MATERIALIZED VIEW */
-	else if (Matches("CREATE", "MATERIALIZED"))
+	else if (Matches("CREATE", "MATERIALIZED") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED"))
 		COMPLETE_WITH("VIEW");
-	/* Complete CREATE MATERIALIZED VIEW <name> with AS or USING */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> with AS or USING */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny))
 		COMPLETE_WITH("AS", "USING");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> USING with list of access
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING with list of access
 	 * methods
 	 */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_table_access_methods);
-	/* Complete CREATE MATERIALIZED VIEW <name> USING <access method> with AS */
-	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
+	/* Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> USING <access method> with AS */
+	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny) ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny))
 		COMPLETE_WITH("AS");
 
 	/*
-	 * Complete CREATE MATERIALIZED VIEW <name> [USING <access method> ] AS
+	 * Complete CREATE [ OR REPLACE ] MATERIALIZED VIEW <name> [USING <access method> ] AS
 	 * with "SELECT"
 	 */
 	else if (Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
-			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "AS") ||
+			 Matches("CREATE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS") ||
+			 Matches("CREATE", "OR", "REPLACE", "MATERIALIZED", "VIEW", MatchAny, "USING", MatchAny, "AS"))
 		COMPLETE_WITH("SELECT");
 
 /* CREATE EVENT TRIGGER */
diff --git a/src/include/commands/view.h b/src/include/commands/view.h
index c41f51b161c..95290f0a1c4 100644
--- a/src/include/commands/view.h
+++ b/src/include/commands/view.h
@@ -22,4 +22,7 @@ extern ObjectAddress DefineView(ViewStmt *stmt, const char *queryString,
 
 extern void StoreViewQuery(Oid viewOid, Query *viewParse, bool replace);
 
+extern void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc,
+							 bool is_matview);
+
 #endif							/* VIEW_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 86a236bd58b..74922f8ae89 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2412,7 +2412,7 @@ typedef struct AlterTableStmt
 typedef enum AlterTableType
 {
 	AT_AddColumn,				/* add column */
-	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE VIEW */
+	AT_AddColumnToView,			/* implicitly via CREATE OR REPLACE [MATERIALIZED] VIEW */
 	AT_ColumnDefault,			/* alter column default */
 	AT_CookedColumnDefault,		/* add a pre-cooked column default */
 	AT_DropNotNull,				/* alter column drop not null */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 6dfca3cb35b..3a0c3b06c81 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -169,6 +169,7 @@ typedef struct IntoClause
 	/* materialized view's SELECT query */
 	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
+	bool		replace;		/* replace existing matview? */
 } IntoClause;
 
 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index c56c9fa3a25..56104b7ee8b 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -694,3 +694,208 @@ NOTICE:  relation "matview_ine_tab" already exists, skipping
 (0 rows)
 
 DROP MATERIALIZED VIEW matview_ine_tab;
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+NOTICE:  materialized view "mvtest_replace" does not exist, skipping
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 1
+(1 row)
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 2
+(1 row)
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+ERROR:  materialized view "mvtest_replace" has not been populated
+HINT:  Use the REFRESH MATERIALIZED VIEW command.
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+ a 
+---
+ 3
+(1 row)
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 4 | 1
+(1 row)
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 4 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     |   reloptions    |     spcname      | amname 
+---+---+----------------+-----------------+------------------+--------
+ 5 | 1 | mvtest_replace | {fillfactor=50} | regress_tblspace | heap2
+(1 row)
+
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+ a | b |    relname     | reloptions | spcname | amname 
+---+---+----------------+------------+---------+--------
+ 5 | 1 | mvtest_replace |            |         | heap
+(1 row)
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+ a | b | a | b 
+---+---+---+---
+ 6 | 1 | 6 | 1
+(1 row)
+
+DROP VIEW mvtest_replace_v;
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 7 | 1
+(1 row)
+
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+                       QUERY PLAN                        
+---------------------------------------------------------
+ Index Scan using mvtest_replace_b_idx on mvtest_replace
+   Index Cond: (b = 1)
+(2 rows)
+
+SELECT * FROM mvtest_replace WHERE b = 1;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+RESET enable_seqscan;
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+ERROR:  cannot change data type of materialized view column "b" from integer to text
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+ERROR:  cannot change name of materialized view column "b" to "b2"
+HINT:  Use ALTER MATERIALIZED VIEW ... RENAME COLUMN ... to change name of materialized view column instead.
+SELECT * FROM mvtest_replace;
+ a | b 
+---+---
+ 8 | 1
+(1 row)
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+ERROR:  cannot change collation of materialized view column "c" from "C" to "POSIX"
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+ERROR:  cannot drop columns from materialized view
+SELECT * FROM mvtest_replace;
+ a  | b | c 
+----+---+---
+ 11 | 1 | y
+(1 row)
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+ERROR:  "mvtest_not_mv" is not a materialized view
+DROP VIEW mvtest_not_mv;
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+ERROR:  syntax error at or near "NOT"
+LINE 1: CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_rep...
+                                               ^
+DROP MATERIALIZED VIEW mvtest_replace;
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 6704eeae2df..fe0cb4d25bf 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -314,3 +314,120 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, BUFFERS OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
 DROP MATERIALIZED VIEW matview_ine_tab;
+
+--
+-- test CREATE OR REPLACE MATERIALIZED VIEW
+--
+
+-- matview does not already exist
+DROP MATERIALIZED VIEW IF EXISTS mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 1 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 2 AS a;
+SELECT * FROM mvtest_replace;
+
+-- replace query without data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 3 AS a
+  WITH NO DATA;
+SELECT * FROM mvtest_replace; -- error: not populated
+REFRESH MATERIALIZED VIEW mvtest_replace;
+SELECT * FROM mvtest_replace;
+
+-- add column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 4 AS a, 1 b;
+SELECT * FROM mvtest_replace;
+
+-- replace table options
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  USING heap2
+  WITH (fillfactor = 50)
+  TABLESPACE regress_tblspace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+-- restore default options
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace
+  AS SELECT 5 AS a, 1 AS b;
+SELECT m.*, c.relname, c.reloptions, s.spcname, a.amname
+  FROM mvtest_replace m
+    CROSS JOIN pg_class c
+    LEFT JOIN pg_tablespace s ON s.oid = c.reltablespace
+    LEFT JOIN pg_am a ON a.oid = c.relam
+  WHERE c.relname = 'mvtest_replace';
+
+-- can replace matview that has a dependent view
+CREATE VIEW mvtest_replace_v AS
+  SELECT * FROM mvtest_replace;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 6 AS a, 1 AS b;
+SELECT * FROM mvtest_replace, mvtest_replace_v;
+DROP VIEW mvtest_replace_v;
+
+-- index gets rebuilt when replacing with data
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 7 AS a, 1 AS b;
+CREATE UNIQUE INDEX ON mvtest_replace (b);
+SELECT * FROM mvtest_replace;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 8 AS a, 1 AS b;
+SET enable_seqscan = off; -- force index scan
+EXPLAIN (COSTS OFF) SELECT * FROM mvtest_replace WHERE b = 1;
+SELECT * FROM mvtest_replace WHERE b = 1;
+RESET enable_seqscan;
+
+-- cannot change column data type
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 9 AS a, 'x' AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot rename column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 10 AS a, 1 AS b2; -- error
+SELECT * FROM mvtest_replace;
+
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 11 AS a, 1 AS b, 'y' COLLATE "C" AS c;
+SELECT * FROM mvtest_replace;
+
+-- cannot change column collation
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 12 AS a, 1 AS b, 'x' COLLATE "POSIX" AS c; -- error
+SELECT * FROM mvtest_replace;
+
+-- cannot drop column
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_replace AS
+  SELECT 13 AS a, 1 AS b; -- error
+SELECT * FROM mvtest_replace;
+
+-- must target a matview
+CREATE VIEW mvtest_not_mv AS
+  SELECT 1 AS a;
+CREATE OR REPLACE MATERIALIZED VIEW mvtest_not_mv AS
+  SELECT 1 AS a; -- error
+DROP VIEW mvtest_not_mv;
+
+-- cannot use OR REPLACE with IF NOT EXISTS
+CREATE OR REPLACE MATERIALIZED VIEW IF NOT EXISTS mvtest_replace AS
+  SELECT 1 AS a;
+
+DROP MATERIALIZED VIEW mvtest_replace;
-- 
2.50.1


--r33ycpluvyfavkwy
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Handle-default-tablespace-in-AlterTableInternal.patch"



^ permalink  raw  reply  [nested|flat] 370+ messages in thread

* [PATCH v48 7/7] Teach snapshot builder to skip transactions running REPACK (CONCURRENTLY).
@ 2026-03-17 19:22  Antonin Houska <ah@cybertec.at>
  0 siblings, 0 replies; 370+ messages in thread

From: Antonin Houska @ 2026-03-17 19:22 UTC (permalink / raw)

During logical decoding, we need to know if particular transaction performed
catalog changes because catalog information is needed to construct heap
tuples. To be sure that we have enough information of each transaction, the
logical decoding cannot start before all the already running transactions have
completed.

The problem with REPACK (CONCURRENTLY) is that it has XID assigned and writes
WAL records marked with it. Thus if another backend runs REPACK (CONCURRENTLY)
and tries to setup the logical decoding, it has to wait for the completion of
all the other transactions involved in REPACK (CONCURRENTLY).

However, REPACK (CONCURRENTLY) does not perform any catalog changes relevant
to logical decoding, so the other backends executing this command can ignore
it. This patch implements it by adding information about transactions
executing the command to the xl_running_xacts WAL record, and by teaching the
snapshot builder to use the information.
---
 src/backend/access/rmgrdesc/standbydesc.c   | 15 ++++-
 src/backend/access/transam/xlog.c           |  2 +
 src/backend/commands/repack.c               | 16 +++++
 src/backend/replication/logical/snapbuild.c | 51 +++++++++-----
 src/backend/storage/ipc/procarray.c         | 75 +++++++++++++++++++--
 src/backend/storage/ipc/standby.c           |  8 ++-
 src/include/storage/standby.h               |  2 +
 src/include/storage/standbydefs.h           |  2 +
 8 files changed, 144 insertions(+), 27 deletions(-)

diff --git a/src/backend/access/rmgrdesc/standbydesc.c b/src/backend/access/rmgrdesc/standbydesc.c
index 0a291354ae2..58ebecf4927 100644
--- a/src/backend/access/rmgrdesc/standbydesc.c
+++ b/src/backend/access/rmgrdesc/standbydesc.c
@@ -21,10 +21,11 @@ standby_desc_running_xacts(StringInfo buf, xl_running_xacts *xlrec)
 {
 	int			i;
 
-	appendStringInfo(buf, "nextXid %u latestCompletedXid %u oldestRunningXid %u",
+	appendStringInfo(buf, "nextXid %u latestCompletedXid %u oldestRunningXid %u oldestRunningXidLogical %u",
 					 xlrec->nextXid,
 					 xlrec->latestCompletedXid,
-					 xlrec->oldestRunningXid);
+					 xlrec->oldestRunningXid,
+					 xlrec->oldestRunningXidLogical);
 	if (xlrec->xcnt > 0)
 	{
 		appendStringInfo(buf, "; %d xacts:", xlrec->xcnt);
@@ -41,6 +42,16 @@ standby_desc_running_xacts(StringInfo buf, xl_running_xacts *xlrec)
 		for (i = 0; i < xlrec->subxcnt; i++)
 			appendStringInfo(buf, " %u", xlrec->xids[xlrec->xcnt + i]);
 	}
+
+	if (xlrec->xcnt_repack > 0)
+	{
+		TransactionId *xids_repack;
+
+		appendStringInfo(buf, "; %d xacts_repack:", xlrec->xcnt_repack);
+		xids_repack = xlrec->xids + xlrec->xcnt + xlrec->subxcnt;
+		for (i = 0; i < xlrec->xcnt_repack; i++)
+			appendStringInfo(buf, " %u", xids_repack[i]);
+	}
 }
 
 void
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 2c1c6f88b74..f1cbdee7618 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -5912,6 +5912,7 @@ StartupXLOG(void)
 				 * subxids are listed with their parent prepared transactions.
 				 */
 				running.xcnt = nxids;
+				running.xcnt_repack = 0;
 				running.subxcnt = 0;
 				running.subxid_status = SUBXIDS_IN_SUBTRANS;
 				running.nextXid = XidFromFullTransactionId(checkPoint.nextXid);
@@ -8483,6 +8484,7 @@ xlog_redo(XLogReaderState *record)
 			 * with their parent prepared transactions.
 			 */
 			running.xcnt = nxids;
+			running.xcnt_repack = 0;
 			running.subxcnt = 0;
 			running.subxid_status = SUBXIDS_IN_SUBTRANS;
 			running.nextXid = XidFromFullTransactionId(checkPoint.nextXid);
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 781a471fc1d..29ba49744eb 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -988,6 +988,22 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose,
 
 	if (concurrent)
 	{
+		/*
+		 * Do not let other backends wait for our completion during their
+		 * setup of logical replication. Unlike logical replication publisher,
+		 * we will have XID assigned, so the other backends - whether
+		 * walsenders involved in logical replication or regular backends
+		 * executing also REPACK (CONCURRENTLY) - would have to wait for our
+		 * completion before they can build their initial snapshot. It is o.k.
+		 * for any decoding backend to ignore us because we do not change
+		 * tuple descriptor of any table, and the data changes we write should
+		 * not be decoded by other backends.
+		 */
+		LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
+		MyProc->statusFlags |= PROC_IN_CONCURRENT_REPACK;
+		ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
+		LWLockRelease(ProcArrayLock);
+
 		/*
 		 * The worker needs to be member of the locking group we're the leader
 		 * of. We ought to become the leader before the worker starts. The
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index 9cf499ce7c6..f2008c6877c 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1172,7 +1172,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	 * xmin, which looks odd but is correct and actually more efficient, since
 	 * we hit fast paths in heapam_visibility.c.
 	 */
-	builder->xmin = running->oldestRunningXid;
+	builder->xmin = running->oldestRunningXidLogical;
 
 	/* Remove transactions we don't need to keep track off anymore */
 	SnapBuildPurgeOlderTxn(builder);
@@ -1188,9 +1188,9 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	 */
 	xmin = ReorderBufferGetOldestXmin(builder->reorder);
 	if (xmin == InvalidTransactionId)
-		xmin = running->oldestRunningXid;
+		xmin = running->oldestRunningXidLogical;
 	elog(DEBUG3, "xmin: %u, xmax: %u, oldest running: %u, oldest xmin: %u",
-		 builder->xmin, builder->xmax, running->oldestRunningXid, xmin);
+		 builder->xmin, builder->xmax, running->oldestRunningXidLogical, xmin);
 	LogicalIncreaseXminForSlot(lsn, xmin);
 
 	/*
@@ -1275,14 +1275,14 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn
 	 * have all necessary catalog rows anymore.
 	 */
 	if (TransactionIdIsNormal(builder->initial_xmin_horizon) &&
-		NormalTransactionIdPrecedes(running->oldestRunningXid,
+		NormalTransactionIdPrecedes(running->oldestRunningXidLogical,
 									builder->initial_xmin_horizon))
 	{
 		ereport(DEBUG1,
 				errmsg_internal("skipping snapshot at %X/%08X while building logical decoding snapshot, xmin horizon too low",
 								LSN_FORMAT_ARGS(lsn)),
 				errdetail_internal("initial xmin horizon of %u vs the snapshot's %u",
-								   builder->initial_xmin_horizon, running->oldestRunningXid));
+								   builder->initial_xmin_horizon, running->oldestRunningXidLogical));
 
 
 		SnapBuildWaitSnapshot(running, builder->initial_xmin_horizon);
@@ -1299,7 +1299,7 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn
 	 * NB: We might have already started to incrementally assemble a snapshot,
 	 * so we need to be careful to deal with that.
 	 */
-	if (running->oldestRunningXid == running->nextXid)
+	if (running->oldestRunningXidLogical == running->nextXid)
 	{
 		if (!XLogRecPtrIsValid(builder->start_decoding_at) ||
 			builder->start_decoding_at <= lsn)
@@ -1378,14 +1378,14 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn
 	/*
 	 * c) transition from BUILDING_SNAPSHOT to FULL_SNAPSHOT.
 	 *
-	 * In BUILDING_SNAPSHOT state, and this xl_running_xacts' oldestRunningXid
-	 * is >= than nextXid from when we switched to BUILDING_SNAPSHOT.  This
-	 * means all transactions starting afterwards have enough information to
-	 * be decoded.  Switch to FULL_SNAPSHOT.
+	 * In BUILDING_SNAPSHOT state, and this xl_running_xacts'
+	 * oldestRunningXidLogical is >= than nextXid from when we switched to
+	 * BUILDING_SNAPSHOT.  This means all transactions starting afterwards
+	 * have enough information to be decoded.  Switch to FULL_SNAPSHOT.
 	 */
 	else if (builder->state == SNAPBUILD_BUILDING_SNAPSHOT &&
 			 TransactionIdPrecedesOrEquals(builder->next_phase_at,
-										   running->oldestRunningXid))
+										   running->oldestRunningXidLogical))
 	{
 		builder->state = SNAPBUILD_FULL_SNAPSHOT;
 		builder->next_phase_at = running->nextXid;
@@ -1402,14 +1402,15 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn
 	/*
 	 * c) transition from FULL_SNAPSHOT to CONSISTENT.
 	 *
-	 * In FULL_SNAPSHOT state, and this xl_running_xacts' oldestRunningXid is
-	 * >= than nextXid from when we switched to FULL_SNAPSHOT.  This means all
-	 * transactions that are currently in progress have a catalog snapshot,
-	 * and all their changes have been collected.  Switch to CONSISTENT.
+	 * In FULL_SNAPSHOT state, and this xl_running_xacts'
+	 * oldestRunningXidLogical is >= than nextXid from when we switched to
+	 * FULL_SNAPSHOT.  This means all transactions that are currently in
+	 * progress have a catalog snapshot, and all their changes have been
+	 * collected.  Switch to CONSISTENT.
 	 */
 	else if (builder->state == SNAPBUILD_FULL_SNAPSHOT &&
 			 TransactionIdPrecedesOrEquals(builder->next_phase_at,
-										   running->oldestRunningXid))
+										   running->oldestRunningXidLogical))
 	{
 		builder->state = SNAPBUILD_CONSISTENT;
 		builder->next_phase_at = InvalidTransactionId;
@@ -1459,6 +1460,24 @@ SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff)
 		if (TransactionIdFollows(xid, cutoff))
 			continue;
 
+		/* Do not wait for transactions running REPACK (CONCURRENTLY). */
+		if (running->xcnt_repack > 0)
+		{
+			TransactionId *xids_repack;
+			int			i;
+
+			xids_repack = running->xids + running->xcnt + running->subxcnt;
+
+			for (i = 0; i < running->xcnt_repack; i++)
+			{
+				if (xid == xids_repack[i])
+					break;
+			}
+			/* Found? */
+			if (i < running->xcnt_repack)
+				continue;
+		}
+
 		XactLockTableWait(xid, NULL, NULL, XLTW_None);
 	}
 
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index cc207cb56e3..033ae68b57e 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2643,15 +2643,25 @@ GetRunningTransactionData(void)
 	RunningTransactions CurrentRunningXacts = &CurrentRunningXactsData;
 	TransactionId latestCompletedXid;
 	TransactionId oldestRunningXid;
+	TransactionId oldestRunningXidLogical;
 	TransactionId oldestDatabaseRunningXid;
 	TransactionId *xids;
 	int			index;
-	int			count;
+	int			count,
+				count_repack;
 	int			subcount;
 	bool		suboverflowed;
+	TransactionId *xids_repack = NULL;
+	bool		logical_decoding_enabled = IsLogicalDecodingEnabled();
 
 	Assert(!RecoveryInProgress());
 
+	/*
+	 * TODO Consider a GUC to reserve certain amount of replication slots for
+	 * REPACK (CONCURRENTLY) and using it here.
+	 */
+#define		MAX_REPACK_XIDS		16
+
 	/*
 	 * Allocating space for maxProcs xids is usually overkill; numProcs would
 	 * be sufficient.  But it seems better to do the malloc while not holding
@@ -2663,11 +2673,14 @@ GetRunningTransactionData(void)
 	 */
 	if (CurrentRunningXacts->xids == NULL)
 	{
+		/* FIXME probably fails if logical decoding is enable on-the-fly */
+		int			nrepack = logical_decoding_enabled ? MAX_REPACK_XIDS : 0;
+
 		/*
 		 * First call
 		 */
 		CurrentRunningXacts->xids = (TransactionId *)
-			malloc(TOTAL_MAX_CACHED_SUBXIDS * sizeof(TransactionId));
+			malloc((TOTAL_MAX_CACHED_SUBXIDS + nrepack) * sizeof(TransactionId));
 		if (CurrentRunningXacts->xids == NULL)
 			ereport(ERROR,
 					(errcode(ERRCODE_OUT_OF_MEMORY),
@@ -2676,7 +2689,10 @@ GetRunningTransactionData(void)
 
 	xids = CurrentRunningXacts->xids;
 
-	count = subcount = 0;
+	if (logical_decoding_enabled)
+		xids_repack = palloc_array(TransactionId, MAX_REPACK_XIDS);
+
+	count = subcount = count_repack = 0;
 	suboverflowed = false;
 
 	/*
@@ -2688,7 +2704,7 @@ GetRunningTransactionData(void)
 
 	latestCompletedXid =
 		XidFromFullTransactionId(TransamVariables->latestCompletedXid);
-	oldestDatabaseRunningXid = oldestRunningXid =
+	oldestDatabaseRunningXid = oldestRunningXid = oldestRunningXidLogical =
 		XidFromFullTransactionId(TransamVariables->nextXid);
 
 	/*
@@ -2697,6 +2713,8 @@ GetRunningTransactionData(void)
 	for (index = 0; index < arrayP->numProcs; index++)
 	{
 		TransactionId xid;
+		int			pgprocno;
+		PGPROC	   *proc;
 
 		/* Fetch xid just once - see GetNewTransactionId */
 		xid = UINT32_ACCESS_ONCE(other_xids[index]);
@@ -2716,6 +2734,21 @@ GetRunningTransactionData(void)
 		if (TransactionIdPrecedes(xid, oldestRunningXid))
 			oldestRunningXid = xid;
 
+		if (logical_decoding_enabled &&
+			TransactionIdPrecedes(xid, oldestRunningXidLogical))
+		{
+			/*
+			 * Backends running REPACK concurrently need to be excluded from
+			 * oldestRunningXidLogical, otherwise the snapshot builder cannot
+			 * proceed in building the initial snapshot.
+			 */
+			pgprocno = arrayP->pgprocnos[index];
+			proc = &allProcs[pgprocno];
+
+			if ((proc->statusFlags & PROC_IN_CONCURRENT_REPACK) == 0)
+				oldestRunningXidLogical = xid;
+		}
+
 		/*
 		 * Also, update the oldest running xid within the current database. As
 		 * fetching pgprocno and PGPROC could cause cache misses, we do cheap
@@ -2723,8 +2756,8 @@ GetRunningTransactionData(void)
 		 */
 		if (TransactionIdPrecedes(xid, oldestDatabaseRunningXid))
 		{
-			int			pgprocno = arrayP->pgprocnos[index];
-			PGPROC	   *proc = &allProcs[pgprocno];
+			pgprocno = arrayP->pgprocnos[index];
+			proc = &allProcs[pgprocno];
 
 			if (proc->databaseId == MyDatabaseId)
 				oldestDatabaseRunningXid = xid;
@@ -2742,6 +2775,19 @@ GetRunningTransactionData(void)
 		 */
 
 		xids[count++] = xid;
+
+		/*
+		 * Collect XIDSs of transactions running REPACK (CONCURRENTLY).
+		 */
+		if (logical_decoding_enabled &&
+			count_repack < MAX_REPACK_XIDS)
+		{
+			pgprocno = arrayP->pgprocnos[index];
+			proc = &allProcs[pgprocno];
+
+			if (proc->statusFlags & PROC_IN_CONCURRENT_REPACK)
+				xids_repack[count_repack++] = xid;
+		}
 	}
 
 	/*
@@ -2782,6 +2828,19 @@ GetRunningTransactionData(void)
 		}
 	}
 
+	/*
+	 * Append the XIDs running REPACK (CONCURRENTLY), if any.
+	 *
+	 * XXX Should we sort the array and use bsearch() when using it?
+	 */
+	if (count_repack > 0)
+	{
+		for (int i = 0; i < count_repack; i++)
+			xids[count++] = xids_repack[i];
+	}
+	if (xids_repack)
+		pfree(xids_repack);
+
 	/*
 	 * It's important *not* to include the limits set by slots here because
 	 * snapbuild.c uses oldestRunningXid to manage its xmin horizon. If those
@@ -2791,11 +2850,13 @@ GetRunningTransactionData(void)
 	 * increases if slots do.
 	 */
 
-	CurrentRunningXacts->xcnt = count - subcount;
+	CurrentRunningXacts->xcnt = count - subcount - count_repack;
 	CurrentRunningXacts->subxcnt = subcount;
+	CurrentRunningXacts->xcnt_repack = count_repack;
 	CurrentRunningXacts->subxid_status = suboverflowed ? SUBXIDS_IN_SUBTRANS : SUBXIDS_IN_ARRAY;
 	CurrentRunningXacts->nextXid = XidFromFullTransactionId(TransamVariables->nextXid);
 	CurrentRunningXacts->oldestRunningXid = oldestRunningXid;
+	CurrentRunningXacts->oldestRunningXidLogical = oldestRunningXidLogical;
 	CurrentRunningXacts->oldestDatabaseRunningXid = oldestDatabaseRunningXid;
 	CurrentRunningXacts->latestCompletedXid = latestCompletedXid;
 
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index de9092fdf5b..fd3e4fe31f3 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -1189,6 +1189,7 @@ standby_redo(XLogReaderState *record)
 		RunningTransactionsData running;
 
 		running.xcnt = xlrec->xcnt;
+		running.xcnt_repack = xlrec->xcnt_repack;
 		running.subxcnt = xlrec->subxcnt;
 		running.subxid_status = xlrec->subxid_overflow ? SUBXIDS_MISSING : SUBXIDS_IN_ARRAY;
 		running.nextXid = xlrec->nextXid;
@@ -1359,10 +1360,12 @@ LogCurrentRunningXacts(RunningTransactions CurrRunningXacts)
 	XLogRecPtr	recptr;
 
 	xlrec.xcnt = CurrRunningXacts->xcnt;
+	xlrec.xcnt_repack = CurrRunningXacts->xcnt_repack;
 	xlrec.subxcnt = CurrRunningXacts->subxcnt;
 	xlrec.subxid_overflow = (CurrRunningXacts->subxid_status != SUBXIDS_IN_ARRAY);
 	xlrec.nextXid = CurrRunningXacts->nextXid;
 	xlrec.oldestRunningXid = CurrRunningXacts->oldestRunningXid;
+	xlrec.oldestRunningXidLogical = CurrRunningXacts->oldestRunningXidLogical;
 	xlrec.latestCompletedXid = CurrRunningXacts->latestCompletedXid;
 
 	/* Header */
@@ -1371,9 +1374,10 @@ LogCurrentRunningXacts(RunningTransactions CurrRunningXacts)
 	XLogRegisterData(&xlrec, MinSizeOfXactRunningXacts);
 
 	/* array of TransactionIds */
-	if (xlrec.xcnt > 0)
+	if (xlrec.xcnt + xlrec.xcnt_repack > 0)
 		XLogRegisterData(CurrRunningXacts->xids,
-						 (xlrec.xcnt + xlrec.subxcnt) * sizeof(TransactionId));
+						 (xlrec.xcnt + xlrec.xcnt_repack + xlrec.subxcnt) *
+						 sizeof(TransactionId));
 
 	recptr = XLogInsert(RM_STANDBY_ID, XLOG_RUNNING_XACTS);
 
diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h
index 6a314c693cd..fe4dcdc3def 100644
--- a/src/include/storage/standby.h
+++ b/src/include/storage/standby.h
@@ -127,10 +127,12 @@ typedef enum
 typedef struct RunningTransactionsData
 {
 	int			xcnt;			/* # of xact ids in xids[] */
+	int			xcnt_repack;	/* # of xacts running REPACK (CONCURRENTLY). */
 	int			subxcnt;		/* # of subxact ids in xids[] */
 	subxids_array_status subxid_status;
 	TransactionId nextXid;		/* xid from TransamVariables->nextXid */
 	TransactionId oldestRunningXid; /* *not* oldestXmin */
+	TransactionId oldestRunningXidLogical;
 	TransactionId oldestDatabaseRunningXid; /* same as above, but within the
 											 * current database */
 	TransactionId latestCompletedXid;	/* so we can set xmax */
diff --git a/src/include/storage/standbydefs.h b/src/include/storage/standbydefs.h
index 231d251fd51..edad609fa9a 100644
--- a/src/include/storage/standbydefs.h
+++ b/src/include/storage/standbydefs.h
@@ -47,10 +47,12 @@ typedef struct xl_standby_locks
 typedef struct xl_running_xacts
 {
 	int			xcnt;			/* # of xact ids in xids[] */
+	int			xcnt_repack;	/* # of xacts running REPACK (CONCURRENTLY) */
 	int			subxcnt;		/* # of subxact ids in xids[] */
 	bool		subxid_overflow;	/* snapshot overflowed, subxids missing */
 	TransactionId nextXid;		/* xid from TransamVariables->nextXid */
 	TransactionId oldestRunningXid; /* *not* oldestXmin */
+	TransactionId oldestRunningXidLogical;
 	TransactionId latestCompletedXid;	/* so we can set xmax */
 
 	TransactionId xids[FLEXIBLE_ARRAY_MEMBER];
-- 
2.47.3


--qfkt2ktdpcfeypib--





^ permalink  raw  reply  [nested|flat] 370+ messages in thread


end of thread, other threads:[~2026-03-17 19:22 UTC | newest]

Thread overview: 370+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v8] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2024-05-21 16:35 [PATCH v7 1/3] Add OR REPLACE option to CREATE MATERIALIZED VIEW Erik Wienhold <ewie@ewie.name>
2026-03-17 19:22 [PATCH v48 7/7] Teach snapshot builder to skip transactions running REPACK (CONCURRENTLY). Antonin Houska <ah@cybertec.at>

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox